Conventional shoulder and hip prostheses typically were unitary structures including an integral stem and neck interconnecting a head. These types of prostheses involve the insertion of the stem in a cavity formed in the femur for a hip prosthesis, or in the humerus for shoulder prosthesis. A problem associated with conventional shoulder and hip prostheses is the need to maintain large inventories of differently configured prostheses for different patient anatomies. Prostheses having a variety of different head sizes, different stem sizes, and different neck angles and radial offsets between the head and stem are required to be kept on hand. Various configurations are required for each size category.
To reduce the required inventory of parts, assorted modular prostheses have been provided. Such systems include differently sized necks, heads and necks with different lengths and angles. While existing modular prosthesis systems allow flexibility with respect to either the neck angle or the radial offset between the head and the stem to accommodate each patient's unique anatomical requirements, improvements are still needed. Some combinations of stems and necks result in a prosthesis that may fail. If the prosthesis fails, the patient must undergo a second operation to remove the failed prosthesis and insert a new prosthesis. It would be desirable to provide a kit and a system comprising a plurality of different sized stems and necks of different lengths and angles that prevent combinations of certain necks with certain stems to prevent failure of the prosthesis.